Morphological, structural, chemical, vibrational, thermal, pasting, and functional changes in pea starch during germination process

Abstract

Background: Changes in the structural and physicochemical properties of pea starch could be significantly affected by germination treatment, which can provide a theoretical basis for promoting the use of this starch in the food industry. Methods: This work aims to evaluate the effect of germination time on the structural, thermal, rheological and functional properties of pea starches to determine their potential in the production of fermented beverages. The physicochemical changes during the germination process of peas and native and germinated starch granules were evaluated. Results: For germination critical time was 0.985 days, with 95% of germinated grains. The starch grains did not undergo any morphological change during the germination process as seen in the scanning electron microscopy images, indicating the absence of the α and ß - amylases responsible for the starch splitting. The X-ray patterns revealed that the crystalline structures of pea starch with and without germination were unchanged and contained by hexagonal and orthorhombic glucopyranose crystals. The viscosity profiles of the starches do not show significant changes; the most representative change is the increase in the gelatinization onset temperature of the paste from germinated starches compared to native starch. The functional properties of starches showed generally low values, with statistically significant differences between water absorption index, water solubility index, and starch swelling power and germination time. Conclusions: In general terms, it can be concluded that lentil starch does not undergo significant changes in its physicochemical and functional integrity with respect to the grain germination process.